Using secrets in your unit tests

I'm having fun creating a small open-source project(more about that later). In a part of this project I need to integrate with an existing API. Of course I want to have the necessary integration tests that help me verify if the integration with this API works correctly. There is only one problem, I need to pass an API key to call this API. How can I safely use and store this API key in my tests without checking the key in as part of my source code?

ASP.NET Core Secret Manager

In your ASP.NET Core application self you can use the Secret Manager Tool. This tool allows you to store your secrets in a separate location from the project tree. This guarantees that the app secrets aren’t checked into source control.

The Secret Manager tool hides implementation details, such as where and how the values are stored. The values are stored in a JSON file in the local machine's user profile folder. For example on Windows:

%APPDATA%\Microsoft\UserSecrets\<user_secrets_id>\secrets.json

In the file path above, the <user_secrets_id> should be replaced with the UserSecretsId value specified in the project file.

More about the Secret Manager here.

The question is:

Can we use the ASP.NET Core Secret Manager also in our unit test projects?

Let’s find out!

Using the Secret Manager in our Unit Test projects

In your unit test project, add the following NuGet Package:

dotnet add package Microsoft.Exensions.Configuration.UserSecrets

After adding the NuGet Package, open the csproj file and add a UserSecretsId property:

Remark: The value for UserSecretsId can be anything as long as it is unique(that is the reason why I added a GUID in the example above).

Now I tried to add the Secret Manager Tool itself:

dotnet add package Microsoft.Extensions.SecretManager.Tools

Unfortunately this doesn’t seem to work and resulted in the following output error:

Package ‘Microsoft.Extensions.SecretManager.Tools 2.0.2’ has a package type ‘DotnetCliTool’ that is not supported by project ‘TestProject’

It turns out that this isn’t such a big problem because you can still right click on the Unit test project in Visual Studio and choose ‘Manage User Secrets’.

This will also load the secrets.json and allow you to add any values:

Using the Secrets in your Unit Test

Now we can setup our tests to use this secret. First we need to build the IConfigurationRoot object:

Through this IConfigurationRoot object we can now load a specific secret value from the secrets.json:

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